Spindle,particularly for textile machines



Sept. 29, 1970 5 GRAU 3,530,657

' SPINDLE, PARTICULARLY FOR TEXTILE MACHINES Filed April 11, 1969 5 Sheets-Sheet l Inventor Sept. 29, 1970 G. GRAU 3,530,657

SPINDLE, PARTICULARLY FOR TEXTILE MACHINES Filed April 11, 1969 3 Sheets-Sheet B FIG.8

In entor Sept. 29, 1970 v GRAU w 3,53

SPINDLE, PARTICULARLY FOR TEXTILE MACHINES 7 Filed April 11, 1969 3 Sheets-Sheet 5 FIG-.15

FIG.16

United States Patent 3,530,657 SPINDLE, PARTI ULARLY FOR TEXTILE M CHINES Gerhard Grau, Ebersbach, Germany, assignor to Zinser- Textilmaschinen-Gesellschaft mit beschrankter Haftung, Ebersbach, Germany, a corporation of Germany Filed Apr. 11, 1969, Ser. No. 815,346 Claims priority, application Germany, Apr. 13, 1968, 1,760,184 Int. Cl. D01h 9/16 US. CI. 5734 33 Claims ABSTRACT OF THE DISCLOSURE The spindle of a textile machine is provided with a yarn cutting device which comprises a driving sleeve member axially slidably held on the spindle and frictionally coupled to the inserted bobbin and a driven sleeve member axially slidably held on the spindle and carrying a knife. When the full bobbin is moved upwardly on the spindle to effect its removal, the driving member is carried axially upward with it. During its axial displacement, the driving member, by means of a worm coupling, imparts a rotary motion to the driven member and the knife, whereby the yarn, leading from the cop to a reserve winding location therebelow and tensioned against the knife, is rapidly and securely severed.

BACKGROUND OF THE INVENTION The invention relates to a spindle used in textile machines, particularly spinning, stretching or doubling frames. The spindle is provided with a cutting device for severing the yarn which extends from a yarn package or cop wound on a bobbin inserted on the spindle to a reserve winding location under the foot of the bobbin. The severing operation is performed automatically as the bobbin is removed from the spindle.

By spindle there is meant the rotatable element of textile machines which twists the yarn and winds it on an associated bobbin.

By bobbin there is meant any type of package or cop carrier such as conical sleeves, spools or the like which may be inserted on the spindle and on which the yarn may be wound to form a cop.

The invention may be particularly advantageously practiced in textile machines of the ring spinning or doubling frame type which are provided with bobbin changers that automatically replace the full bobbins with empty ones.

By yarns there are meant any type of textile yarns, such as twisted yarns, synthetic yarns or the like.

In textile machines to which this invention relates, a yarn reserve winding is performed on each spindle upon completion of a cop. Such winding is formed of a few wraps of yarn about the reserve winding location which is disposed axially under the bobbin foot.

During the removal of the full bobbin, the yarn portion which extends from the cop to the reserve winding location, has to be severed. If it is out too late, or not cut at all, it may run off the cop unsevered and may thus cause operational troubles.

Various cutting devices are known for severing the yarn extending to the reserve Winding location. According to a known arrangement, above the reserve winding location there is provided a peripherally knurled spindle rim integral with the spindle axle and forming, with its projections, a fixation device that firmly holds the yarn extending from the cop to the reserve winding location. The yarn is broken during the removal of the full bobbin. It was found, however, that often the yarn was not severed in time or was not cut at all. It is known to obviate this 3,530,657 Patented Sept. 29, 1970 disadvantage by securing on the spindle a carrier member which is axially and rotatably movable with respect thereto, and the rotation of which with the spindle is arrested by an abutment when the bobbin attains its position for removal. Said carrier member comprises two parts rotatable about the spindle in a direction opposed to one another; one part carries a severing knife, while the other carries a yarn clamp. As soon as the position of removal is reached, the yarn clamp is temporarily driven until it draws the yarn taut over the immobile severing knife, whereupon the latter cuts the yarn. Such a device, which is described, for example, in German Pat. No. 875,015, is complicated, delicate and susceptible to operational failures. In addition, it requires a complex control of the spinning frame and the spindle drive. Further, the severing of the yarn is performed as a separate step, whereby the bobbin changing operation is lengthened and thus, productivity is impaired.

OBJECTS AND SUMMARY OF THE INVENTION A principal object of the invention is to provide an improved yarn cutting device for spindles used in textile machines wherein the disadvantages of known cutting devices are eliminated.

It is a further object of the invention to provide an improved cutting device of the aforenoted type which is simple, operates reliably, and which securely severs the yarn at an early moment during the removal of the full bobbin when the latter is only a few millimeters or centimeters axially above its normal operating position.

It is a further object of the invention to provide an improved cutting device of the aforenoted type wherein the severing of the yarn is performed in such a manner that the force necessary to remove the full bobbin is not substantially increased which is a significant feature particularly in automatic bobbin changers, since the axial forces exerted on the bobbins for their removal are decreased and the bobbin gripping device may be constructed in a simpler manner.

It is still another object of the invention to provide an improved, simple cutting device of the aforenoted type which, instead of tearing, mechanically severs the yarn, whereby the appearance of usually very high tearing forces are avoided, together with all inherent disadvantages.

Briefly stated, according to the invention, there is provided a yarn cutting device of the aforenoted type which comprises a yarn severing member rotatably mounted on the spindle and disposed under the bobbin inserted thereon. The cutting device further includes a driving member slidably held on the spindle and adapted to be carried axially to a limited extent by the full bobbin by virtue of a disconnectable bobbin coupling means while said bobbin is in the process of upward removal. Thus, the full bobbin, during its removal from the spindle, carries with it the said driving member until the latter is arrested in its axial movement by an abutment. During its axial movement, the driving member moves a driven member which, in turn, causes the severing member to perform the cutting operation. The axially sliding driving member causes a rotational motion of a driven member and the severing member about the spindle axis. As a result, the yarn portion, which is tensioned between the cop and the reserve winding location is rapidly and securely cut.

The invention will be better understood as well as further objects and advantages will become more apparent from the ensuing detailed specification of five 6xemplary embodiments taken in conjunction with the drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a partially sectional elevational view of a first embodiment of the invention in its position of rest;

FIGS. 2 and 3 are elevational views of a portion of the first embodiment depicting different positions during the removal of the bobbin;

FIG. 4 is an elevational view of a second embodiment in its position of rest;

FIG. 5 is a sectional view taken along line VV of FIG. 4;

FIGS. 6 and 7 are elevational views of the second embodiment depicting different operational positions during the removal of the bobbin;

FIG. 8 is a partially sectional elevational view of a third embodiment of the invention in its position of rest;

FIG. 9 is a perspective, fragmentary view of the severing member of the third embodiment at the beginning of the upward motion of the bobbin;

FIGS. 10 and 11 are similar to FIG. 9, depicting the severing member in difierent operational positions during the removal of the bobbin;

FIG. 12 is a sectional elevational view of a fourth embodiment of the invention in its position of rest;

FIG. 13 is a view similar to FIG. 12 depicting the fourth embodiment in an operational position during the removal of the bobbin;

FIG. 14 is a sectional elevational view of a fifth embodiment of the invention in its position of rest; and

FIGS. 15 and 16 are fragmentary perspective views of two modifications of a component shown in FIGS. 1-3.

DESCRIPTION OF THE PREFERRED EMBODIMENT Turning now to FIGS. 1-3, the spindle 1, which is of conventional structure in all nonillustrated details, is rotatably held on a bearing sleeve, not shown. The spindle is driven in a conventional manner by a belt (also not show) which is trained about an only partially shown whorl 3. Immediately above the whorl 3 there is fixed- 1y secured to the spindle a rotationally symmetric knurled metal ring 4- whose knurled portion immediately adjacent the rim 5 of the whorl 3' forms a reserve winding location 6 for a yarn 7 wound thereon with several wraps at the end of a preceding winding operation. A yarn portion 7' of the yarn 7 extends from the cop 9 wound on a bobbin 8 during the preceding winding process to the reserve winding location 6, from where the yarn portion 7" leads, in a known and therefore not shown manner, through a traveller arranged on a spinning or doubling ring, to the delivery system of the associated textile machine, also not shown. The purpose of the reserve winding of the yarn is to prevent breaking of the yarn portion 7" during the removal of the full bobbin 8, 9.

After the insertion of a new, empty bobbin 8, the winding of a new cop 9 may start without the necessity of a new positioning the yarn.

The spindle is provided with a cutting device indicated at 3 for severing the yarn portion 7' during the removal of the full bobbin from the spindle axle 2. The cutting device 3 comprises two fixation members 11, 22, a worm gear drive assembly 15 (including a driving member 19 and a driven member 14) and a severing member 17, the structure and operation of which will be discussed hereinafter in greater detail.

The knurled upper rim of the metal ring 4 constitutes the first yarn fixation member 11 which prevents the yarn portion 7 lying thereagainst immediately above the reserve winding location 6 from being displaced in the circumferential direction of the spindle during the removal of a full bobbin.

The spindle axle 2 of the spindle 1 is provided with a cylindrical bearing face 12 which is delimited by the first fixation member 11 and by a shoulder 13. On bearing face 12 there is rotatably held a tubular cylindrical driven member 14 which is part of worm gear drive assembly 15 and which has on its outer face a largepitch, helically extending rib 16. particularly well seen in FIGS. 2 and 3. The lower end of driven member 14, carries, integral therewith, a circular knife 17, which constitutes the severing member of the cutting device 3. By designing the severing member as an integral rim of the driven member, a substantial saving of space may be achieved. As a result, a cutting device so designed is also adapted for use on small spindles. The cutting edge of knife 17 has a diameter larger than that of the first fixation member 11. The driven member 14 is coaxially surrounded in a formfitting manner by a tubular driving member 19, which has a helical groove 16 complemental with and interengaging rib 16. The worm coupling 16, 16 has a large pitch: it is preferably at least 25. The driving member 19 and the driven member 14 constitute the worm gear drive assembly 15. Above the bearing face 12, the spindle axle 2 is provided with a cylindrical guiding face 20 which guides the driving member 19 during its axial upward displacement. A shoulder 21 delimits the guiding face 20 at its upper end and forms an abutment for limiting the upward displacement of the driving member 19. The radial shoulder 17' of the circular knife 17 forms an abutment determining the lowermost position of the driving member 19. Thus the latter is axially displaceable on the spindle axle 2 between the shoulders 17' and 21.

The driving member 19 is designed in such a manner that the bobbin foot 8' may be inserted thereon and frictionally engaged thereby. For this purpose, the outer circumference of the driving member 19 carries two spaced snap rings 18 which form a detachable frictional coupling between the inserted bobbin 8 and the driving member 19. The driving member 19 terminates in its lower portion in a rim 22 which has several functions. It serves as an abutment for the bobbin foot 8', thus determining the lowermost position of bobbin 8. Further, by virtue of its circumferential knurls, it serves as a second yarn fixation member disposed above the severing member 17, in order to prevent the yarn, drawn taut thereagainst during the removal of the full bobbin 8, from being displaced in the circumferential direction of the spindle axle 2. The bobbin 8 is frictionally connected with the head (not shown) of the spindle axle 2 in a known manner and thus may not rotate relative to the spindle axle. Consequently, the driving member 19, despite an absence of a separate antirotational locking means, is prevented by the inserted bobbin 8 from rotating with respect to the spindle axle 2.

In FIG. 1, the cutting device 3 is shown in its normal position (position of rest) during the winding of the cop 9. In this position the cutting edge of the circular knife 17 lies immediately adjacent the underside of the second yarn fixation member 22 so that the latter forms a guard about the circular knife 17. Since the diameter of the circular knife 17 is slightly smaller than that of the yarn fixation member 22, an accidental contact with the cutting edge and thus possible injury to an attendant is prevented.

OPERATION OF THE FIRST EMBODIMENT After completing a cop 9, the yarn 7 is wound about the reserve winding location 6. Thereafter the full bobbin 8, 9 may be lifted off the spindle axle 2 and a new, empty bobbin may be inserted thereon. During the removal of the full bobbin, the yarn portion 7 extending to the reserve winding location 6 is securely and rapidly severed by means of the cutting device 3 shown in successive positions in FIGS. 1-3. During the removal of the full bobbin 8, performed, for example, by an automatic bobbin changer, the driving member 19, due to its frictional coupling with bobbin 8, is carried therewith upwardly in the direc tion of arrow D. By virtue of the cooperation between the complemental interengaging helical elements 16, 16' of the worm gear drive assembly 15, the driven member 14 and thus the circular knife 17 are turned in the direction of the arrow D. During the axial displacement of the driving member 19, the yarn is tensioncd across the circular knife 17 which, during its afore-described rotation, severs the tensioned yarn as shown in FIG. 3. The

driving member 19, carried axially upwardly by the bobbin 8, is stopped by the abutment shoulder 21, and, upon a continuing upward movement of the bobbin 8, is separated from the latter. As soon as the driving member 19 is disengaged from bobbin 8, the former may, by virtue of its own weight, slide back into its position of rest shown in FIG. 1. Should such a return of driving member 19 be prevented by friction, it is forcibly return into its position shown in FIG. 1 by a newly inserted empty bobbin exerting a downward force on the rim 22. Thereupon a new winding process may begin.

DESCRIPTION OF THE SECOND EMBODIMENT The embodiment shown in FIGS. 4-7 and mounted on spindle 23 may be identical in all nonrepresented details to the first embodiment with the exception that the yarn fixation member 25 firmly secured to the reserve winding location 24 and the yarn fixation member 27 firmly secured to the driving member 26 are provided with circumferentially arranged teeth 29 as best shown in FIG. 5. The teeth 29 are substantially rectangular so that the spaces between adjacent teeth form gaps 30 which may engage the yarn portion 7' extending to the reserve winding location 24. Thus, during the removal of the bobbin 8, the yarn is securely prevented from shifting in the circumferential direction of the spindle 23.

The driving member 26, which is visible only in FIG. 5, is identical to the driving member 19 of the first embodiment with the exception of its yarn fixation member 27. It forms the outer part of worm gear drive assembly 31, while the inner part thereof is formed of driven member 32 designed identically to driven member 14 of the first embodiment. The severing member 33 formed as an integral part of driven member 32 is not a circular knife as in the first embodiment but an annular disc having circumferential teeth 34 which correspond in structure to the circumferential teeth 29 (FIG. 5) of the yarn fixation members 25, 27. Facing sides of adjacent teeth 34 define gaps 35. The two yarn fixation members 25, 27 and the severing member 33 are of identical diameter and are axially spaced in their position of rest (FIG. 4) by means of cylindrical spacer rings 36, 37 secured to either side of the severing member 33.

OPERATION OF THE SECOND EMBODIMENT The cop 9 is wound on the bobbin 8 frictionally coupled with the driving member 26, while the cutting device is in its position of rest (FIG. 4). Upon termination of the winding operation, the yarn 7 is wound about the reserve winding location 24. Thereupon, the full bobbin 8, 9 may be lifted off (FIGS. 6 and 7). During the removal of bobbin 8, 9, the driving member 26 is displaced axially upwardly in the direction of arrow B and turns the severing member 33 mounted rotatably on the spindle axle 23' in the direction of arrow B. The severing member 33 tensions the yarn portion 7' which is prevented from a displacement in the circumferential direction of the spindle by the two yarn fixation members 25, 27 and then severs it (FIG. 7). In order to facilitate the cutting of the yarn, the horizontal radial edges of teeth 29 of the severing member 33 are sharpened.

DESCRIPTION OF THE THIRD EMBODIMENT Turning now to FIG. 8, there is shown a spindle 40 having a spindle axle 42, a whorl 43 and a knurled reserve winding location 44 disposed above the whorl.

The spindle axle 42 carries a Worm gear drive assembly 49 formed of a driven member 47 and a driving member 50. The driven member 47 is rotatably held on and relative to a cylindrical bearing face of spindle axle 42, While the driving member 50 coaxially surrounds the driven member 47 in a formfitting manner. Members 47 and 50 are drivingly coupled by means of a helically extending, complemental and interengaging rib 59 (integral with driven member 47) and groove 59 (integral with driving member 50).

To the driving member 50 there is circumferentially attached a spring ring 53 formed of a plurality of axially extending, circumferentially juxtaposed and radially outwardly arcuate leaf spring elements 54 (only one shown) constituting a coupling for frictionally connecting the inner face of bobbin foot 8 with the driving member 50.

Immediately above the reserve winding location 44 and integral with the spindle axle 42 there is disposed a first shearing element 45 which cooperates with a second shearing element 46 integral with the lower end of the driven member 47 and urged axially against the first shear ing element 45 by a coil spring 51 disposed about spindle axle 42 and engaging the upper radial terminal face of driven member 47. The shearing elements 45, 46 constitute the severing member in this embodiment.

The driving member is limited in its axial displacement by a shoulder terminating a cylindrical bearing face 52 for the driving member 50 and by the upper radial face of the second shearing element 46.

The two shearing elements 45, 46 as shown in FIGS. 9- 11, having at their circumference a plurality of radial projections 55, 56 of trapezoid cross section. The engaging large faces of projections 55, 56 are urged towards one another by means of the coil spring 51 (FIG. 8). The radial, horizontal edges (such as 57) of the large faces, are sharpened to form cutting edges which, like shears, cooperate and serve to sever the yarn portion 7 leading to the reserve winding location 44.

OPERATION OF THE THIRD EMBODIMENT Upon termination of a winding operation, the yarn is wound around the reserve winding location 44. Thereupon, the full bobbin 8 is lifted upwardly and during this motion it carries therewith in the direction of arrow E the driving member 50' frictionally coupled to bobbin 8 by means of spring 53. By virtue of the cooperation between groove 59' and rib 59, the driven member 47 and thus the second shearing element 46 rotate in the direction of the arrow B (FIGS. 10, 11). As the full bobbin 8 moves upward, the yarn portion 7', leading to the reserve winding location 44, is tensioned and pressed against the two shearing elements 45, 46, so that it assumes a position in a gap between two pairs of projections 55, 56 as illustrated in FIG. 9. As the shearing element 46 rotates, the two cutting edges 57 flanking the tensioned yarn, cooperate and sever the same (FIG. 11).

The driving member 50, carried axially upwardly by the bobbin 8, is stopped by the abutment shoulder 60 and, upon continued upward movement of the bobbin 8, is separated from the latter. Thereupon, the driving member 50 may slide back by gravity into its position of rest (-FIG. 8) or may be forcibly returned thereto by a downwardly moving new empty bobbin.

DESCRIPTION OF THE FOURTH EMBODIMENT The spindle 61 shown in FIGS. 12 and 13 comprises a spindle axle 63 including an axle sleeve 69 keyed to core 67 and an adjoining axle portion having a whorl 64, a rim 65 disposed thereabove and a reserve winding location 66 situated above rim 65.

The cutting device '62 comprises a worm gear drive assembly 71 formed of a driven member 71 rotatably held on a cylindrical bearing face 70 of axle sleeve 69 and a driving member 72 coaxially surrounding the driven member 71. There too, the driving connection between driving and driven members is formed of a large-pitch, interengaging, complemental rib and groove coupling indicated at 72.

The driven member 71 has, at its lower end, a circular knife 79.

The rotationally symmetrical driving member 72 has an upper head portion 74 slidably engaging a guiding face 75 of the axle sleeve 69 and a conical outer face 73 adapted to frictionally engage the inner face of the foot of an inserted bobbin 8. The lower part of the driving memher 72 terminates in a circular, flared portion, a cylindrical outer face 77 of which is knurled and serves as a yarn fixation member. The said flared portion includes a downwardly open conical cavity 90 in which the circular knife 79 may nest when the driving member 72 is in its lowermost position (position of rest) as shown in FIG. 12. Thus, in this position, the flared portion of driving member 72 acts as a shield or guard for the circular knife 79.

The axial movement of driving member 72 is limited by a snap ring 76 secured to axle sleeve 69 (uppermost position) and by an upper radial face of circular knife 79 (lowermost position).

OPERATION OF THE FOURTH EMBODIMENT Upon termination of a winding operation, the yarn is wound about the reserve winding location 66. Thereupon the full bobbin 8, 9 is lifted off the spindle in the direction of the arrow C, carrying therewith upwardly the driving member 72 until the latter abuts against the snap ring 76. During the axial displacement of the actuating member 72, the latter, by virtue of worm coupling 72, rotates, through the driven member 71, the circular knife 79. As the driving member 72 is moved upward, the circular knife 79 becomes exposed so that the yarn (not shown) leading to the reserve winding location 66 lies against the circular knife 79 under tension and is rapidly and easily severed by virtue of the rotation of the latter.

Should the own weight of the driving member 72 not be sufiicient to return the same into its position of rest (FIG. 12) after separation from the bobbin, it is expe dient to design the coupling 72 as a left-hand worm in case of a right-hand twisted yarn, and, as a right-hand worm, in case of a left-hand twisted yarn. If, in such a design, the spindle is driven without a bobbin thereon, the actuating member slides by inertia into its position of rest (FIG. 12) in which the cylinder knife 79 is shielded.

DESCRIPTION OF THE FIFTH EMBODIMENT The spindle 91 shown in FIG. 14 is provided with a cutting device 92 comprising a worm gear drive assembly 92' formed of a driven member 96 rotatably held on a cylindrical bearing face 95 of the spindle axle 94 and a driving member 100 coaxially surrounding the driven member 96. The driving connection between driving and driven members is formed of a single large-pitch, interengaging, complemental rib and groove coupling 89, 89'.

The driven member 96 is urged downwardly against rim 97 of spindle axle 94 by a coil spring 103. The reserve winding location 93 in this embodiment is rotatable about the spindle axle 94 and is formed as a knurled cylindrical portion of the driven member 96. Above the reserve winding location 93 the driven member 96 carries an integral circular knife 99.

The driving member 100 terminates, at its lower end, in a rim 101 having a diameter slightly greater than that of circular knife 99. Thus, in the lowermost position of driving member 100, the rim 101 rests against the circular knife 99 and constitutes a guard therefor. The driving member 100 is provided with spring means 102, the structure and purpose of which are identical to those of spring 53 of the third embodiment (FIG. 8): it frictionally couples the driving member 100 with the bobbin 8 shown in broken lines.

The bearing face 95 is joined by a guiding face 104 of larger diameter for the driving member 100. The guiding face 104 terminates at a shoulder 105 which serves as an abutment for limiting the upward axial displacement of the driving member 100.

The worm coupling 89, 89' is designed in such a manner that during an upward displacement of the driving member 100 in the direction of arrow A, the driven member 96, together with the reserve winding location 93 and the circular knife 99, is turned in the direction of yarn winding (arrow A), so that the yarn leading from the cop to the reserve winding location is tensioned during fit the removal of the bobbin and is pressed against the exposed circular knife 99 which, as it rotates, rapidly and securely severs the yarn.

The cutting device designed according to the fifth embodiment shown in FIG. 14 is particularly adapted for textile machines which are not equipped with automatic bobbin changers and in which the spindles are driven by a gear wheel drive in a formfitting manner.

It is to be understood that the cutting edge of the circular knife 17 (first embodiment), 79 (fourth embodiment) or 99 (fifth embodiment) may be smooth, or may be designed as a fine saw (as shown in FIG. 15) or file (as shown in FIG. 16).

What is claimed is:

1. In a spindle of the type including a spindle axle adapted to receive a bobbin for winding a yarn thereon to form a cop, a reserve winding location disposed axially below said bobbin to receive a plurality of wraps of yarn extending from said cop, said bobbin, upon completion of said cop, being adapted to be axially slidably removed from said spindle, a yarn cutting device mounted on said spindle axle and adapted to automatically sever the yam between said cop and said reserve winding location when said full bobbin is axially displaced for removal, the improvement in said cutting device comprising,

(A) a driving member held on said spindle axle and axially slidable with respect thereto,

(B) a separable coupling means connecting said driving member with said bobbin to cause said driving member to be drawn from a position of rest axially with said bobbin during the removal thereof,

(C) a driven member held on said spindle axle and rotatable with respect thereto,

(D) a driving connection coupling said driving member with said driven member to cause rotation of the latter when the former is axially displaced,

(E) a severing member connected with said driven member and adapted to rotate therewith, said severing member, during said rotation of said driven member, cutting said yarn tensioned between said cop and said reserve winding location and (F) abutment means axially fixed with respect to said spindle axle to limit the extent of axial displacement of said driving member.

2. An improvement as defined in claim 1, wherein said 0 severing member is a circular knife coaxial with, and

rotatable relative to, said spindle axle.

3. An improvement as defined in claim 2, wherein said circular knife has a smooth cutting edge.

4. An improvement as defined in claim 2, wherein said circular knife has a cutting edge formed of saw teeth.

5. An improvement as defined in claim 2, wherein said circular knife has a cutting edge formed of a file.

6. An improvement as defined in claim 2, including an axially movable guard circumferentially shielding the cutting edge of said circular knife at least when said driving member is in its position of rest.

7. An improvement as defined in claim 6, wherein said guard is formed of a radially extending enlargement of one end of said driving member.

8. An improvement as defined in claim 7, wherein said enlargement is a radial rim having a diameter slightly larger than that of the cutting edge of said circular knife; said rim has a lower radial face adapted to abut against an upper radial face of said circular knife in said position of rest.

9. An improvement s defined in claim 7, wherein said enlargement has a downwardly open conical cavity coaxial with said circular knife; the latter is adapted to nest in said cavity when said driving member is in said position of rest.

10. An improvement as defined in claim 7, wherein said enlargement has an outer circumferential portion serving as a fixation member adapted to engage said yarn between said cop and said reserve winding location for preventing said yarn from circumferential displacement during operation of said circular knife.

11. An improvement as defined in claim 1, wherein said severing member is a disk coaxial with, and rotatable relative to, said spindle axle, said disk is provided on its periphery with radially extending teeth defining gaps therebetween, the yarn between said cop and said reserve winding location is adapted to lie in one of said gaps and is adapted to be severed by a radially extending edge of a tooth upon rotation of said disk. 12. An improvement as defined in claim 1, wherein said severing member is formed of two cooperating, adjoining and relatively rotatable shearing elements coaxial with said spindle axle.

13. An improvement as defined in claim 12, wherein one of said shearing elements is fixed with respect to said reserve winding location.

14. An improvement as defined in claim 12, wherein one of said shearing elements is integral with said driven member.

15. An improvement as defined in claim 1, including means for preventing axial displacement of said driven member during axial motion of said driving member.

16. An improvement as defined in claim 15, wherein said last named means includes a spring axially urging said driven member against an abutment axially fixed with respect to said spindle axle.

17. An improvement as defined in claim 1, wherein said driving and driven members are coaxially arranged sleeves mounted on said spindle axle.

18. An improvement as defined in claim 17, wherein said driving connection is formed of a worm coupling comprising a rib integral with one of said sleeves and a groove provided in the other of said sleeves; said rib extends into said groove and is slidable therein.

19. An improvement as defined in claim 17, wherein said separable coupling means is adapted to establish a frictional engagement between said driving member and said bobbin.

20. An improvement as defined in claim 19, wherein said separable coupling means is adapted to establish a frictional engagement between said driving member and the inner face of said bobbin inserted on said spindle axle.

21. An improvement as defined in claim 20, wherein said separable coupling means comprises at least one snap ring coaxially affixed to the outer face of said driving member.

22. An improvement as defined in claim 20, wherein said separable coupling means comprises a spring ring coaxially afiixed to the outer face of said driving member, said spring ring includes a plurality of axially extending, circumferentially juxtaposed and radially outwardly arcuate leaf spring elements.

23. An improvement as defined in claim 20, wherein said separable coupling means comprises a conical frictional surface constituting the outer face of said driving member.

24. An improvement as defined in claim 1, wherein at least one part of said severing member is formed by a rim integral with a lower end of said driven member.

25. An improvement as defined in claim 1, wherein at least one part of said severing member is fixed with respect to said reserve winding location.

26. An improvement as defined in claim 1, including at least one fixation member surrounding said spindle axle and adapted to engage said yarn between said cop and said reserve winding location for preventing said yarn from circumferential displacement during operation of said severing member.

27. An improvement as defined in claim 26, wherein said fixation member has a plurality of circumferentially arranged teeth defining gaps therebetween, said yarn is adapted to pass through one of said gaps to be laterally straddled by the teeth defining said last named gap.

28. An improvement as defined in claim 26, wherein said fixation member has a knurled, cylindrical surface.

29. An improvement as defined in claim 26, wherein said fixation member is integral with said driving member.

30. An improvement as defined in claim 26, wherein said fixation member is affixed to said spindle axle.

31. An improvement as defined in claim 26, wherein the fixation members are two in number and are disposed axially at either side of said severing member.

32. An improvement as defined in claim 1, including a further abutment determining the lowermost position of said bobbin on said spindle axle.

33. An improvement as defined in claim 32, wherein said further abutment is formed by a rim surrounding said spindle axle, said rim has an outer face which constitutes a fixation member adapted to engage said yarn between said cop and said reserve winding location for preventing said yarn from circumferential displacement during operation of said severing member.

References Cited UNITED STATES PATENTS 3,186,154 6/1965 Negishi 57-54 3,210,922 10/1965 Winter 5754 3,263,409 8/1966 Zuidema 57-34 XR 3,283,489 11/1966 Bakker 5734 3,284,026 11/1966 Zuidema 57-34 XR JOHN PETRAKES, Primary Examiner US. or. XIR. s7- s4; 242 1s 

